Diffractive Jet Production in Deep-Inelastic e^+p Collisions at HERA

TL;DR

This paper reports measurements of dijet and 3-jet cross sections in diffractive deep-inelastic scattering at HERA, providing insights into the diffractive gluon distribution and testing various theoretical models.

Contribution

It presents the first detailed measurement of jet cross sections in diffractive DIS, constraining the diffractive gluon distribution and testing models like 2-gluon exchange.

Findings

Data consistent with a diffractive exchange trajectory intercept near 1.2

Results tightly constrain the diffractive gluon distribution

Models based on 2-gluon exchange reproduce cross section shapes at low x_pom

Abstract

A measurement is presented of dijet and 3-jet cross sections in low-|t| diffractive deep-inelastic scattering interactions of the type ep -> eXY, where the system X is separated by a large rapidity gap from a low-mass baryonic system Y. Data taken with the H1 detector at HERA, corresponding to an integrated luminosity of 18.0 pb^(-1), are used to measure hadron level single and double differential cross sections for 4<Q^2<80 GeV^2, x_pom<0.05 and p_(T,jet)>4 GeV. The energy flow not attributed to jets is also investigated. The measurements are consistent with a factorising diffractive exchange with trajectory intercept close to 1.2 and tightly constrain the dominating diffractive gluon distribution. Viewed in terms of the diffractive scattering of partonic fluctuations of the photon, the data require the dominance of qqbarg over qqbar states. Soft colour neutralisation models in their present form cannot simultaneously reproduce the shapes and the normalisations of the differential cross sections. Models based on 2-gluon exchange are able to reproduce the shapes of the cross sections at low x_pom values.